The present invention is directed to a semiconductor processing reactor and in particular to a reactor which causes material to sputter from the wafer being processed.
During semiconductor fabrication processes including but not limited to etch processes, material from a wafer may have a tendency to sputter therefrom and deposit on various surfaces, including but not limited to cooler surfaces, of a reactor such as the walls of a reactor. Inductively coupled plasma reactors generally have a first power electrode which can be in the shape of a inductive coil which is coupled to the reactor chamber through a window which is generally comprised of quartz. In such a arrangement, material sputtered from a wafer and traveling in a direct line-of-sight, can strike and build-up on the various surfaces of the reactor including the walls and the window. Such deposits caused by sputtering and other mechanisms can adversely affect the operation of the reactor. The build-up of such materials means that the reactor must be periodically shut down and the various surfaces are either cleaned or replaced. Accordingly, there is a need to minimize the effect of material sputtered from the wafer surface, which is deposited on the walls and window of the reactor. Further, there is a need to minimize the effect of materials deposited by any mechanism on the walls, windows, and other surfaces of a reactor.
The present invention is directed to overcome the disadvantages of the prior art. In particular, the present invention is advantageously useful for semiconductor wafer processing operations that cause materials to sputter from the surface of a wafer. In particular, in the case of a inductively coupled plasma reactor having an electrode in the form of an inductive coil coupled to the reactor chamber through a power transfer window, deposited materials, including but not limited to metals and other materials deposited by sputtering and other mechanisms, could impinge and collect upon the window reducing or eliminating the power coupling from the inductive electrode.
Accordingly, it is an object of the present invention to provide a mechanism whereby the sputtering of the materials from the wafer does not reduce or eliminate the power coupling from the inductive electrode or any other electrodes.
It is another object of the present invention to provide a deposition shield that prevents the deposition of materials on a power transfer window or an electrode. Deposition could occur through mechanisms such as sputtering, condensation, and the like.
It is another object of the present invention to provide a deposition shield to intercept material sputtered from the wafer surface that is directed toward the electrode and/or the window which couples the electrode to the reaction chamber.
It is a further object of the present invention to provide a deposition shield that is in the direct line-of-sight or sputter path between the wafer and the electrode or window.
It is a further object of the present invention to provide for a reactor which has a longer operational mean time between shutdown for maintenance and cleaning.
Yet a further object of the present invention is to provide a shield which is comprised of material which affects the character of a plasma formed in the reactor.
Yet another object of the present invention is to provide a shield which is comprised of one of a conductor and non-conductor such as an insulator.
Still a further object of the present invention is to provide a shield which allows an electrical field to continue through the shield from a first chamber to a second chamber where a wafer is held by a chuck.
Yet another object of the present invention is to provide a shield comprised of, by way of example only, conductors such as aluminum, annodized aluminum, carbon (graphite), and carbon based compounds containing graphite.
In still a further object of the present invention, the shield is comprised of an insulator including, by way of example only, one of alumina, quartz, teflon, delrin, nylon, polyimide, and a support structure coated with an organic compound, and generally carbon based compounds (plastics).
Still a further object of the present invention is to provide a shield which protects a wafer held on a chuck in a second chamber from generation of a plasma.
In accordance with the invention, a plasma reactor includes an electrode which is used to create a plasma and a reactor chamber. The reactor includes a chuck that is adapted to hold the wafer, which chuck is located in the reactor chamber. The reactor further includes a deposition shield which is located in the reactor chamber in the line-of-sight path between the wafer and the electrode.
In another aspect of the invention, the deposition shield includes a plurality of louvers or slats.
In a further aspect of the invention, the deposition shield includes a plurality of overlapping louvers or slats which block the line-of-sight path between the wafer and the electrode in order to block the path of materials removed from the wafer, by methods including but not limited to sputtering, and directed toward the electrode.
In yet a further aspect of the invention, the plasma reactor is an inductively coupled plasma reactor and the reactor includes a window which shields the electrode from the reactor chamber. The deposition shield prevents materials from being deposited onto the window and thereby reducing or eliminating the power coupling from the inductive electrode which is coupled through the window to the reactor chamber.
In another aspect of the invention, the shield is comprised of material which affects the character of the plasma.
In still another aspect of the invention, the shield is comprised of one of a conductor and an insulator.
In another aspect of the invention, the plasma reactor includes a tri-electrode reactor with a first electrode located at the top of the reactor, a second electrode located about the periphery of the chamber, and a third electrode located at the bottom of the chamber and associated with the chuck which holds a wafer. The top electrode can include, by way of example only, a capacitively coupled electrode.
In another aspect of the invention and in particular with an inductively coupled plasma reactor, a device is provided for preventing the reduction or elimination of the power coupling of a inductive electrode, which is coupled to the reactor chamber through a window.
In another aspect of the invention, the deposition shield allows for effective operation of ICP (Inductively Coupled Plasma) systems and ECR (Electron Cyclotron Resonance) systems.
Other aspects, objects and advantages of the invention will be evident from a review of the specification, the claims and the appended drawings.